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Engine fire warning on the ground? Evacuation?

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Engine fire warning on the ground? Evacuation?

Old 23rd Sep 2010, 18:45
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Engine fire warning on the ground? Evacuation?

Is it allowed to discharge two bottle without 30 second interval in case of engine fire on the ground in boeing737? FCTM b737 page 8.12? Give me advise please, how do you make decision for evacuation in case of RTO due to engine fire? Thank you!!!
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Old 23rd Sep 2010, 19:06
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Smoke and/or fire = evacuate.

No smoke and/or fire = hesitate.
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Old 23rd Sep 2010, 19:10
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Don't just rely on the lights and bells. It is easy to forget that you can open the window, stick your head out and see for yourself.
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Old 23rd Sep 2010, 20:36
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You seem to have posed two questions here, one having to do with discharging a second fire bottle and the other having to do with evacuation based on an on-ground fire

I see no harm in discharging a fire bottle on the ground, seeing as it shuts off the fuel to the engine, causes any air leaks or fire to subside and in most cases will extinguish a real fire confined to a nacelle. At the same time you sure have no need of engine power while stoppd on the ground.

The idea about waiting before discharging a second bottle is to determine if the first one made the problem go away giving one a chance to think what do do next (stick your head out the window, page the crew in the back etc.).

Based on the results of the above, now consider an evacuation.

I'll now take a deep breath and see what others have to say about this.
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Old 23rd Sep 2010, 20:57
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seeing as it shuts off the fuel to the engine
- firing a bottle does nothing to the fuel supply.

There is no time restriction on firing the second bottle. Evacuation - that is what you are paid to decide.
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Old 23rd Sep 2010, 21:11
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Originally Posted by Bobik737 View Post
Is it allowed to discharge two bottle without 30 second interval in case of engine fire on the ground in boeing737? FCTM b737 page 8.12? Give me advise please, how do you make decision for evacuation in case of RTO due to engine fire? Thank you!!!
You'll need to read it careful. It says:

If an engine fire warning light is NOT illuminated, but a fire indication exists or a fire is reported in or near an engine, discharge BOTH fire bottles.

As for your question in regards to evacuate or not, it is a tough call. You need to give it careful thought wether to evacuate or not, when in doubt, evacuate.

As Boeing points out, use all relevant sources to confirm fire is out...Make sure the airplane is parked in a position, that if the fire relights, it is on the downwind side....
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Old 23rd Sep 2010, 21:34
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In my 737 ops manual in the chapter concerning evacuation - bottle discharge:
"Rotate and hold fire switches until the bottle discharge lights illuminate. In case of eng fire, discharge BOTH bottles in affected engine. Wait 30 seconds before discharging the second bottle in the affected engine as the time that the agent (halon) is on the fire is more important than the amount of agent on the fire."
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Old 23rd Sep 2010, 21:47
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What section of the FCTM are you referring to and what is the date on your manual?
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Old 23rd Sep 2010, 22:55
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Pulling the fire switch does indeed cut fuel supply to the engine. The switch has to be pulled to arm the bottle, ergo, the fuel is cut off, no?
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Old 24th Sep 2010, 03:50
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As has been stated, the Halon 1301 used is a gaseous extinguishing agent. It works by being heavy and inert: it sits around and prevents oxygen from reaching the fire while absorbing the heat. Very little of it should chemically react.

The nacelle has been engineered to maintain the proper concentration. It should work a bit better on the ground since you're not moving and the atmospheric pressure is higher. Since its 5 times denser than air, it will stick around for minutes.

If you fire the second bottle too early, all you'll do is push out the existing Halon to the atmosphere and waste it. Another concern is that because how Halon absorbs heat, when it touches hot components they will rapidly cool and cause thermal shock and major engine damage.

I'd say to go ahead and pull the handles, but as the checklist says, pilot judgement is necessary before the first bottle. Wait 30 seconds for the second bottle, but evacuate in the meantime if necessary.
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Old 24th Sep 2010, 07:34
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This was actually queried at a fairly high level (I think it was in BA) and the word was there is no need to wait 30 seconds on the ground. I suspect, reivilo, that we are looking at company specific OMs , as my last company SPECIFICALLY detailed that you do not need to wait. We follow the book (subject to our discretion, of course!)

Pmonkey - correct, but the words were "discharging a fire bottle on the ground, seeing as it shuts off the fuel to the engine" - when the fuel is already off.

Incidentally, the logic in discharging both bottles when there is evidence of a fire in the vicinity is to avoid the bottles exploding in any fire and thus if you abort for some non-fire related event you need to consider before firing the bottles. The same reason goes for discharging the APU bottle.
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Old 24th Sep 2010, 08:08
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Leaving aside type specifics, waiting 30s to discharge a second bottle with a Fire on the Ground seems "unwise"? Surely that is delaying the Evacuation by up to 30s?

The company I work for's bottom line is you evacuate for 'Any Confirmed Unextinquished Fire'. That can be interpreted in a number of ways, but my thinking is along the lines of:
  1. A Fire Warning (alone) is not Confirmed
  2. 'Unextinquished' is at the (final) point of the Evac decision.
Whilst that decision could be immediate, in practice, while my colleague is working through the Fire Drill, I am confirming the Fire / communicating (windows, ATC, CC etc.). If it is confirmed, we will invariably now go for the Evac checklist. That requires certain actions prior the actual Evacuation becoming irreversible, and another chance to see if the fire has extinquished.

As ever, there is no "right" and "wrong". You make the decision, and unless it is patently wrong given the info you had at the time, you should be supported. Whether a more optimal answer subsequently becomes apparent is not too relevant - you can only act on the info and training at that time. PPRuNe will of course hang you, but what's new

NoD
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Old 24th Sep 2010, 09:40
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...Halon 1301 used is a gaseous extinguishing agent. It works by being heavy and inert: it sits around and prevents oxygen from reaching the fire while absorbing the heat. Very little of it should chemically react.
I'm not a chemist but I was under the impression that the exact opposite was the case: the whole effectiveness of halon-like suppressants comes from their ability to interfere with combustion processes at the atomic level, once broken down by heat. The cooling/smothering effects are welcome but secondary...

See: SKYbrary - Halon Fire Extinguishers
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Old 24th Sep 2010, 10:12
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Originally Posted by BOAC
I suspect, reivilo, that we are looking at company specific OMs , as my last company SPECIFICALLY detailed that you do not need to wait. We follow the book (subject to our discretion, of course!)
You're correct, its quoted from my company specific OM.


Originally Posted by NigelOnDraft
Leaving aside type specifics, waiting 30s to discharge a second bottle with a Fire on the Ground seems "unwise"? Surely that is delaying the Evacuation by up to 30s?
No, you would not delay the evacuation because the order to evacuate is given prior to discharging any fire bottle:

7 Engine start levers (both) . . . . . CUTOFF
8 Advise the cabin to evacuate.
9 Advise the tower.
10 Engine and APU fire switches (all) . . . . Override and pull
11 If an engine or APU fire warning occurs: Illuminated fire switch . . . . . . . . . . Rotate to the stop and hold for 1 second

Last edited by reivilo; 24th Sep 2010 at 10:45.
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Old 24th Sep 2010, 15:14
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Cool

Incidentally, the logic in discharging both bottles when there is evidence of a fire in the vicinity is to avoid the bottles exploding in any fire
The bottles will not explode as they have a pressure relief built in. Remember the little red discs on the pylons for 747 and near the apu, that was/is your relief indication, nowadays it's by a light in the cockpit of the modern jets.
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Old 24th Sep 2010, 15:30
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I guess it was taught as 'belt and braces'? There is no other reason.
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Old 24th Sep 2010, 20:49
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I'm not a chemist but I was under the impression that the exact opposite was the case: the whole effectiveness of halon-like suppressants comes from their ability to interfere with combustion processes at the atomic level, once broken down by heat. The cooling/smothering effects are welcome but secondary...
I've heard that, but I've also heard that's a traditional explanation. I've been told that it appears that by having a heavy inert molecule, you get plasma interactions which suppress the flame. Check out the DARPA instant fire suppression project, it turns out we know less of fire than we thought.

The new clean agents, Novec 1230 and FM-200 don't have any bromine, iodine or chlorine and are even heavier than Halon. The former of which looks like it's going to replace airframe halon completely on the A350.
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Old 25th Sep 2010, 10:42
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What section of the FCTM are you referring to and what is the date on your manual?
Boeing FCTM 737 ,9 revision June 2010,page 8.12
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Old 25th Sep 2010, 11:07
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Another simple question... RTO after engine fire warning in low visibility, information from ATC and nearby aircraft conforming fire is impossible to receive, parking brake is set, cabin crew informed. Engine fire memory action completed by captain or f/o?
Second bottle discharged after 30 sec interval?
What procedures of your company say?
Thank you!!!
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Old 26th Sep 2010, 13:49
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Engine fire on ground after RTO in low Vis:Recall items and discharge BOTH bottles WITHOUT waiting 30 secs.
I believe the 30 secs in the air is in case you discharge one and the fire signal stops you may keep the second bottle in case the fire comes back....on the ground if the fire comes back after both bottles discharged..evacuate.

If still sign of fire :Parking Brake set,Speed brake stow,Call for flaps 40 then QRH checklist.
When time comes to call for evacuation, check fire situation one last time(may have extinguished by then).

Fo will advise tower of evacuation and approximate position for fire rescue.


Capt becomes PF if stop call is made hence he performs recall items.
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